A matching pair of “anti-immigration activists” has been charged with bombing a diversity office in Arizona.

PHOENIX  —  Twin brothers have been indicted in a 2004 mail bombing that injured the diversity director of the Arizona city of Scottsville.

Dennis and Daniel Mahon are charged with conspiracy to damage buildings and property by means of explosive, according to an indictment unsealed Thursday and filed June 16 in federal court.

The indictment says the brothers, who live in Illinois, intended to “promote racial discord” on behalf of the White Aryan Resistance.

The package detonated in Don Logan’s hands on Feb. 26, 2004, in the city’s Human Resources Complex. Logan oversaw diversity issues for city employees and citizens, including racial and sex discrimination. The blast injured Logan’s hand and arm. A secretary also was injured, and both spent about a week in the hospital.

Authorities arrested the brothers in their Davis Junction, Illinois, home and say they had assault weapons, hundreds of rounds of ammunition and white supremacist material.